Buy.com offers Ken Burns' The National Parks: America's Best Idea on DVD
. That's the lowest total price we could find by $12, although we saw it for $7 less last winter. This 6-disc set includes the 12-hour documentary from PBS plus more than three hours of bonus content.
Update: Family Video offers it for $39.99 plus $1.99 for shipping. That's $3 less than the price above. Also, a reader notes that Family Video offers the Blu-ray Disc version for $49.99 plus $1.99 for shipping, a price low of $8.